ANNAPOLIS, JULY 13 -- Taking a cue from the group 2 Live Crew, a mysterious rap artist has been making waves here this week by jamming a marine radio frequency normally reserved for boats in distress with his own blue-streaked lyrics.

The man everyone is calling "the Rapper" made his bawdy broadcast debut on Channel 16, the international station for mayday calls, Monday afternoon and has been heard intermittently on the Chesapeake Bay ever since, often several times an hour, said U.S. Coast Guard Petty Officer Jim Crouse.

"It's just filth, yelling profanities and everything you could probably think of that you shouldn't say on the radio," Crouse said of the broadcaster's monologues, some of which have been in rap. "A lot of boaters were getting on and yelling at him to shut up, but he just yelled back."

Aside from the annoyance, marine officials here say the man's antics are a genuine hazard because only one person can use the emergency frequency at a time. His broadcasts could block out a call for help, particularly because boats in distress usually operate on low power and their communications are easily lost.

According to Annapolis Harbor Master Rick Dahlgren, the rapper's stream-of-consciousness broadcasts have been hard to avoid because most boaters remain tuned to Channel 16 when they are out on the water, in case they run into trouble or to make it easy to contact each other.

"We have to keep the channel on in my office. And you get real tired of hearing all that garbage," Dahlgren said. "This guy is into, 'You can't catch me. Ha, ha, ha, I can say anything I want and blankety-blank-blank you.' "

Martin Lucas, harbor master at the Annapolis City Marina, tuned into Channel 16 on Wednesday night and heard the rapper singing a song "he changed all the words to, like it was his own radio show." According to Lucas, the man also said, "I have my white friend's boat, and I'm messing with all you honkies."

Coast Guard officials in Baltimore recorded the rapper's expletive-filled performance Tuesday evening, when he was on the air for two hours and 11 minutes.

He invited listeners to buy "a little nose candy" and gave a long description of his location and the name of his boat, which turned out to be false, said Petty Officer Mark Williams. In fact, the rapper may not be broadcasting from a boat at all.

Although misuse of Channel 16 by children and drunken sailors is not uncommon, the length and explicitness of the rapper's diatribe is, according to Williams. Therefore, although the Coast Guard often ignores radio pirates with the hope they will get bored and stop, officials are trying to locate the rapper.

Williams said Coast Guard operators in Baltimore have tracked the man's radio signal to the Severn River, which stretches 14 miles from Annapolis to northern Anne Arundel County, and feel confident they will find him. If he is using a standard marine radio, his monologue is probably only being received within a 15 to 20 mile radius, Williams said.

Under Federal Communications Commission rules, misuse of an emergency frequency is an offense punishable by a $10,000-a-day fine. Giving false distress messages is a misdemeanor with a penalty of a $100,000 fine and a year's imprisonment.